JP2591103B2 - Fuel injection control device for internal combustion engine with EGR device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention [Industrial Application Field] The present invention relates to an internal combustion engine provided with an exhaust gas recirculation device (hereinafter, referred to as an EGR device) for recirculating a part of exhaust gas of an internal combustion engine to an intake system. The present invention relates to a fuel injection control device for an internal combustion engine with an EGR device that performs appropriate fuel injection when the engine decelerates.

2. Description of the Related Art Conventionally, there has been proposed a fuel injection control device for an internal combustion engine that adapts an injected fuel amount to a required fuel amount of the internal combustion engine so that fuel injected and supplied to the internal combustion engine is favorably burned. Since the required fuel amount of the internal combustion engine is generally determined by the load of the internal combustion engine, in the conventional fuel injection amount control device for the internal combustion engine,
Various sensors for detecting the load of the internal combustion engine, for example, an air flow meter or an intake pressure sensor, a rotational speed sensor, and the like, are provided, and in order to inject and supply a fuel amount suitable for a required fuel amount calculated based on the detection result, The fuel injection time is determined, and the amount of injected fuel is finely adjusted.

Meanwhile, some internal combustion engines include an EGR device that controls the amount and timing of recirculation of exhaust gas in accordance with the rotation speed and load of the internal combustion engine in order to reduce NOx contained in the exhaust gas. Such an EGR device is provided with a control valve (hereinafter referred to as EG) in an exhaust recirculation path connecting an intake system and an exhaust system of an internal combustion engine.
A designated opening of the EGR valve is determined by a control signal determined according to the rotational speed and load of the internal combustion engine (for example, Japanese Patent Laid-Open No. 59-2214).
No. 67, "Engine control device", etc.).

[Problems to be Solved by the Invention] However, in the fuel injection control device for an internal combustion engine with an EGR device, the following problems occur at the time of rapid deceleration such as at the time of a shift change.

When the internal combustion engine is rapidly decelerated, such as at the time of a shift change, the command opening of the EGR valve output to the EGR device becomes a small value in accordance with a sudden decrease in the load on the internal combustion engine.
However, when the operating speed of the EGR valve is not fast, the actual opening of the EGR valve cannot catch up with the indicated opening temporally, and becomes larger than the indicated opening. For this reason, at the time of sudden deceleration when the EGR valve is originally closed or almost required to be closed,
The EGR valve is kept open, and a large amount of EGR gas continues to flow into the intake system.As a result, combustion becomes unstable, causing misfires and increasing unburned HC emissions and drivability. There was a problem that worsened.

The present invention has been made in view of the above problems, and EGR
It is an object of the present invention to provide a fuel injection control device for an internal combustion engine with an EGR device which prevents a decrease in emission and a deterioration in drivability during deceleration of the internal combustion engine provided with the device.

Configuration of the Invention [Means for Solving the Problems] In order to achieve the above object, the present invention has the following structures as means for solving the problems. That is,
The fuel injection control device for an internal combustion engine with an EGR device according to the present invention comprises an operating state detecting means M2 for detecting an operating state of an internal combustion engine M1 including a load, as exemplified in a basic configuration diagram of FIG. A fuel injection means M3 for receiving a detection result of the state detection means M2 and injecting a fuel amount corresponding to a load of the internal combustion engine M1 into the internal combustion engine M1, an exhaust system M4 and an intake system M5 of the internal combustion engine M1. A control valve M7 is provided in the connected exhaust recirculation path M6, and the degree of opening of the control valve M7 is controlled in response to a control signal S from the outside to recirculate a part of exhaust gas to the intake system M5. Means M8, receiving a detection result of the operation state detecting means M2, and outputting an instruction opening degree of the control valve M7 corresponding to the load of the internal combustion engine M1 to the exhaust gas recirculation means M8 as the control signal S. A fuel injection control device for an internal combustion engine with an EGR device, comprising: Based on the detection result of the state detection unit M2, a deceleration state determination unit M10 that determines whether the internal combustion engine M1 is in a deceleration state, and an actual opening of the control valve M7 of the exhaust gas recirculation unit M8 is detected. Actual opening degree detecting means M11, and a difference obtained by subtracting the instruction opening degree output from the instruction opening degree outputting means M9 from the actual opening degree detected by the actual opening degree detecting means M11 is not less than a predetermined value. Difference determining means M1 for determining
2, when the deceleration state determination unit M10 determines that the vehicle is in a deceleration state, and when the difference determination unit M12 determines that the difference is equal to or greater than a predetermined value, the fuel injection by the fuel injection unit M3 is performed. And a fuel injection stopping means M13 for stopping the supply.

[Operation] The fuel injection control device for an internal combustion engine with an EGR device according to the present invention configured as described above receives the detection result of the operating state detection unit M2, and responds to the load of the internal combustion engine M1 by the fuel injection unit M3. Injects and supplies the fuel amount to the internal combustion engine M1, receives the detection result of the operating state detecting means M2, and controls the command opening of the control valve M7 according to the load of the internal combustion engine M1 by the command opening output means M9. S is output to the exhaust gas recirculation means M8. When the deceleration state determination means M10 determines that the internal combustion engine M1 is in the deceleration state, the control valve M7 detected by the actual opening degree detection means M11 is output. From the actual opening of the instruction opening degree output means
When the difference obtained by subtracting the indicated opening degree output in M9 is determined to be equal to or more than a predetermined value by the difference determination means M12, the fuel injection means M3 stops supplying fuel.

Therefore, when the internal combustion engine M1 is decelerating, the control valve M7
When the actual opening of the internal combustion engine M8 does not catch up with the commanded opening received by the exhaust gas recirculation means M8 and becomes larger than the commanded opening, the fuel injection to the internal combustion engine M1 is stopped, The combustion of the engine M1 is temporarily stopped.

EXAMPLES Hereinafter, preferred examples of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a schematic configuration diagram showing an internal combustion engine for a vehicle equipped with a fuel injection control device for an internal combustion engine with an EGR device according to an embodiment of the present invention and peripheral devices thereof.

As shown in FIG. 1, intake air passing through an air cleaner 6 flows into an intake pipe 4 of the internal combustion engine 2. The air cleaner 6 is provided with an intake air temperature sensor 8 for detecting an intake air temperature. The amount of intake air passing through the intake pipe 4 is adjusted by opening and closing control of a throttle valve 10, and a throttle opening sensor 12 is provided to detect the opening of the throttle valve 10. A surge tank 14 for suppressing pulsation of intake air is formed further downstream of the intake pipe 4. An intake pressure sensor 16 for detecting an absolute pressure (intake pressure) in this tank.
Is provided.

On the other hand, an exhaust pipe 18 of the internal combustion engine 2 has an air-fuel ratio sensor 20 for detecting an air-fuel ratio of a fuel mixture supplied to the internal combustion engine 2 from an oxygen concentration in the exhaust gas and a three-way catalytic converter 22 for purifying the exhaust gas. Is provided. Further, the exhaust pipe 18 is provided with an EGR device 24 that recirculates exhaust gas to the intake pipe 4 to recirculate exhaust gas.

The EGR device 24 has a configuration in which an EGR valve 28 is provided in an exhaust gas recirculation path 26 connecting the exhaust pipe 18 and the upstream of the surge tank of the intake pipe 4. The EGR valve 28 is provided with a step motor rotor 28a in accordance with a pulse signal from an electronic control circuit described later.
Is rotated, the lift amount of the valve body 28b changes, and the opening area of the valve changes.
By controlling the opening of the EGR valve 28, the intake pipe 4
The amount of exhaust gas recirculated to is controlled.

The distributor 32 distributes the high voltage output from the igniter 34 to the ignition plugs 36 of the respective cylinders in synchronization with the crank angle of the internal combustion engine 2, and the ignition timing of the ignition plug 36 is the high voltage from the igniter 34. It is determined by the output timing.

In order to detect the operating state of the internal combustion engine 2, the above-described intake air temperature sensor 8, throttle opening sensor 12,
In addition to the intake pressure sensor 16 and the air-fuel ratio sensor 20, a rotation speed sensor 38 for detecting the rotation speed of the internal combustion engine 2 from the rotation of the rotor 32a of the distributor 32,
The cylinder discriminating sensor 40 outputs a pulse signal once every two rotations of the crankshaft of the internal combustion engine 2 in accordance with the rotation of the internal combustion engine 2, the water temperature sensor 42 which detects the cooling water temperature of the internal combustion engine 2, and is provided near the axle according to the vehicle speed. A vehicle speed sensor 44 for generating a pulse signal is provided.

The detection signals from the sensors are output to an electronic control circuit 46 configured as a logic operation circuit centered on a microcomputer. The electronic control circuit 46 drives the fuel injection valve 48 to control the fuel injection amount to the internal combustion engine 2 based on these detection signals, drives the igniter 34 to control the ignition timing, and controls the EGR valve 28 To perform EGR control.

The electronic control circuit 46 has a CPU 50 that executes various arithmetic processes for the control according to a preset control program, and a control program and initial data necessary for executing the arithmetic processes in the CPU 50 are stored in advance. ROM52, C
A RAM 54 in which various data are temporarily read and written to assist the arithmetic processing performed by the PU 50, a clock signal generation circuit 56 that generates a clock signal that determines a control timing necessary for performing the arithmetic processing in the CPU 50, Input port 58 for inputting detection signals from each sensor, and EGR
It comprises an output port 60 for outputting a drive signal to the valve 28, the fuel injection valve 48 or the igniter 34.

Next, an EGR control routine and a fuel injection control routine, which are main processes according to the present invention, which are executed by the electronic control circuit 46, will be described with reference to FIGS.

FIG. 3 is a flowchart showing an EGR control routine. This routine is executed as one process of a main routine that is repeatedly executed during a period from the start of the internal combustion engine 2 to the stop of the operation.

When the process is started, first, the throttle opening sensor 1
2, based on the detection results of the intake pressure sensor 16, the rotational speed sensor 38 and the water temperature sensor 42, the throttle opening degree TA and the intake pipe pressure P
A process of reading M, the engine speed NE, and the cooling water temperature THW is performed (step 100). Subsequently, by determining whether the read values of the throttle opening TA and the cooling water temperature THW satisfy predetermined conditions,
It is determined whether or not the operation state of the internal combustion engine is in an exhaust gas recirculation region (EGR region) (step 110). Here, if it is determined that the engine speed is in the EGR range, a process of calculating the command opening TSTEP of the EGR valve 28 from the engine speed NE and the intake pipe pressure PM read in step 100 is performed (step 12).
0). The indicated opening TSTEP is determined by the engine speed NE and the intake pipe pressure PM.
And is calculated based on the indicated opening degree map as shown in FIG. 7 stored in the ROM 52 in advance. In FIG. 7, the value between each cell is obtained by interpolation calculation. After execution of step 120, the processing of this routine ends.

On the other hand, if it is determined in step 110 that the area is not the EGR area, the processing of step 120 is skipped, and the processing of this routine ends. The command opening degree TSTEP calculated by the EGR control routine is transmitted to the EGR valve via the output port 60.
28, and determines the opening degree of the EGR valve 28.

FIG. 4 is a flowchart showing a fuel injection control routine. This routine is also executed as one process of a main routine that is repeatedly executed during a period from the start of the internal combustion engine 2 to the stop of the operation.

When the process is started, first, a TAU calculation process for calculating a fuel injection time TAU is executed (step 200). This processing is performed by executing the flowchart of FIG. 5. This processing will be described below with reference to FIG.

When the process is started, first, the throttle opening sensor 1
2.From the detection results of the intake pressure sensor 16, the rotational speed sensor 38, the water temperature sensor 42, etc., the throttle opening TA, the intake pipe pressure
The PM, the engine speed NE, the cooling water temperature THW, and the like are each read (step 210), and a process of calculating a basic fuel injection time TP from the engine speed NE and the intake pipe pressure PM is executed (step 220). The basic injection time TP is defined by a two-dimensional map of the engine speed NE and the intake pipe pressure PM, and based on such a basic injection time map previously stored in the ROM 52, the basic injection time TP Is calculated. Next, from the engine speed NE and the intake pipe pressure PM,
A process for calculating an EGR fuel correction coefficient FEGR is executed (step 230). The EGR fuel correction coefficient FEGR is also defined by a two-dimensional map of the engine speed NE and the intake pipe pressure PM. Based on such an EGR fuel correction coefficient map stored in the ROM 52 in advance, FEGR is Is calculated. Subsequently, the basic fuel injection time TP is multiplied by the EGR fuel correction coefficient FEGR to obtain the EGR
The basic injection time TP taking into account the effect of
240). Subsequently, various fuel correction coefficients f based on the throttle opening TA, the coolant temperature THW, etc. read in step 210 are calculated (step 250), and the various fuel correction coefficients f are added to the basic fuel injection time TP calculated in step 240. To calculate the fuel injection time TAU (step 260). Step 26
After the execution of 0, the process exits from “RETURN” and moves to step 300 in FIG.

In step 300, the intake pressure sensor 16, the rotation speed sensor 3
8 and the detection result of the speed sensor 44, the intake pipe pressure PM,
The engine speed NE and the vehicle speed SPD are read, respectively, and then, based on the read intake pipe pressure PM, the one stored in step 320, which will be described later, when the routine was last processed.
Subtract the previous intake pipe pressure PMO to calculate the intake pipe pressure difference △ PM
Is calculated (step 310). Subsequently, the intake pipe pressure PM read in step 300 is stored as the previous intake pipe pressure PMO (step 320).

After execution of step 320, the process proceeds to step 330, where RA
A process for reading the instruction opening TSTEP and the actual opening RSTEP stored in M54 is executed. The instruction opening NTSTEP is a value indicating the opening of the EGR valve 28, which is calculated in the EGR control routine, as described above, whereas the actual opening RSTEP is the current opening of the EGR valve 28. It indicates the degree of opening, and R
It is calculated by a STEP calculation routine. The RSTEP calculation routine will be described next.

This routine is a process executed by interruption for a predetermined period of time, and every 8 msec in this routine. When the process is started, first, the instruction opening TSTEP calculated by the EGR control routine
Is determined to be equal to the actual opening RSTEP previously calculated in the present routine (step 400). Here, if it is determined that the two are not equal, then it is determined whether or not RSTEP is greater than TSTEP (step 410). Where RSNEP
If it is determined that> TSTEP, the actual opening RSTEP is incremented by 1 (step 420), and if it is determined that RSTEP ≦ TSTEP, the actual opening RSTEP is decremented by 1 (step 430). After the execution of step 420 or step 430, the processing of this routine ends. Meanwhile, step 40
When it is determined that the instruction opening TSTEP is equal to the actual opening RSTEP, the processing of steps 410 to 430 is skipped, and the processing of this routine ends.

According to the RSTEP calculation routine, when the command opening TSTEP is output in the EGR control routine to control the opening of the EGR valve 28, the actual opening RSTEP is set to one step every 8 msec interrupt time of this routine. Will be updated. In such a configuration, the operation delay time from when the EGR valve 28 receives the opening degree instruction to when the EGR valve 28 actually reaches the opening degree takes 8 msec for one step. By calculating the EGR valve
28 current actual opening RSTEP are calculated.

Returning to FIG. 4, in step 330, the designated opening TSTEP and the actual opening are set.
When RSTEP is read, the processing moves to the following step 500. In step 500, it is determined whether or not the internal combustion engine 2 is in a deceleration state by determining whether or not the intake pipe pressure difference ΔPM calculated in step 310 is smaller than 0. Here, when it is determined that the vehicle is in the deceleration state, the determinations in the following steps 510 to 540 are executed.

That is, it is determined whether or not the vehicle speed SPD read in step 300 is higher than 20 km / h (step 510), whether the engine speed NE read in step 300 is higher than 2000 rpm (step 520), The designated opening TSTEP read in step 330 is the actual opening RS also read in step 330.
Judgment whether it is smaller than TEP (step 530), and TS
It is determined whether or not the absolute value of the value obtained by subtracting RSTEP from TEP is greater than a predetermined value A (step 540). If all the determinations in steps 510 to 540 are affirmative, the process proceeds to step 550. In step 550, the fuel injection time TAU calculated in step 200 is set to a value of 0, a fuel cut process for stopping the fuel injection is executed, and then the process of this routine ends. On the other hand, if it is determined in step 500 that the vehicle is not in the deceleration state, or if a negative determination is made in any one of steps 510 to 540, the fuel cut processing in step 550 is skipped, and the processing of this routine ends.

According to the fuel injection control routine described above, when the internal combustion engine 2 is decelerated such that the intake pipe pressure PM decreases, the vehicle speed SPD is greater than 20 km / h, and the engine speed NE is 2000 rpm.
When the actual opening RSTEP of the EGR valve 28 is larger than the instruction opening TSTEP by a predetermined value A or more and later than the instruction opening TSTEP, the amount of fuel injected from the fuel injection valve 48 is cut. I do.

Next, the operation and effect of the fuel injection control device configured as described above will be described with reference to FIG.

When the internal combustion engine is decelerated as at the time of a shift change (time t1), the throttle opening TA decreases, the intake pipe pressure PM of the internal combustion engine 2 decreases, and according to the decrease in the intake pipe pressure PM, EGR is performed. The command opening TSTEP output to the valve 28 becomes a small value. However, since the operation speed of the EGR valve 28 is not high, the actual opening RSTEP of the EGR valve 28 is
Is temporally delayed from the commanded opening TSTEP, and is larger than the commanded opening TSTEP. For this reason, conventionally, a large amount of unnecessary EGR gas has continuously flowed into the intake system, and as a result, combustion has become unstable, causing misfire.

On the other hand, according to the fuel injection control device of the present embodiment, when the delay of the actual opening RSTEP with respect to the command opening TSTEP is equal to or more than the predetermined value, in this embodiment, the fuel cut process is executed. , Fuel injection is stopped (time
t2). For this reason, the combustion of the internal combustion engine 2 is stopped, and without causing unstable combustion, misfire is prevented. As a result, the emission of unburned HC is reduced, the emission can be improved, and the drivability can be improved. Note that the actual opening RST for the commanded opening TSTEP
If the delay of the EP is within the A step, the execution of the fuel cut processing is stopped (time t3), and the normal fuel injection control is performed.

Further, according to the present embodiment, when the internal combustion engine 2 is decelerated, the EG
The actual opening RSTEP of the R valve 28 is a predetermined value A from the indicated opening TSTEP.
Even in the case where the vehicle speed SPD increases, the fuel cut is not executed when the vehicle speed SPD is equal to or less than 20 km / h or the engine speed NE is equal to or less than 2000 rpm. For this reason, at the time of low-speed or low-speed rotation, by performing the fuel cut, it is possible to prevent a traveling shock that an occupant may feel. The vehicle speed SPD is 20km / h
When the engine speed becomes larger or the engine speed NE becomes larger than 2000 rpm, the driving shock caused by the fuel cut is very small and not noticeable by the occupants. That is, according to the present embodiment, the emission at the time of sudden deceleration can be improved without reducing the drivability at low speed or low rotation.

In the above-described embodiment, the deceleration state determination unit M10 is configured to detect a decrease in the intake pipe pressure PM. However, the deceleration state determination unit M10 may be configured to detect a decrease in the throttle opening TA instead. You may.

In addition, as the actual opening degree detecting means M11, it is configured by a RESTEP calculation routine executed by the electronic control circuit 46, but instead of this, a position for detecting the lift position of the valve element 28b in the EGR valve 28 is used. A sensor may be provided, and the output of the position sensor may be used.

As mentioned above, although one Example of this invention was described in full detail, this invention is not limited to such Examples at all, and can be implemented in various aspects within the range which does not deviate from the summary of this invention. Of course it is.

Effect of the Invention As described in detail above, according to the fuel injection control device for an internal combustion engine with an EGR device of the present invention, when the internal combustion engine is decelerating, the actual opening degree of the control valve of the exhaust gas recirculation means increases Even if it does not catch up with the commanded opening of the control valve output to the recirculation means, and there is a large difference from the commanded opening, no misfire occurs and as a result, the amount of unburned HC emissions decreases and emissions And drivability can be improved. Further, as a secondary effect, the fuel injection is stopped, so that the fuel efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram showing a basic configuration of a fuel injection control device for an internal combustion engine with an EGR device according to the present invention, and FIG. 2 is a vehicle equipped with a fuel injection control device for an internal combustion engine with an EGR device according to one embodiment. FIG. 3 is a schematic diagram showing an internal combustion engine for use in a vehicle and its peripheral devices. FIG. 3 is a flowchart of an EGR control routine executed by the electronic control circuit. FIG. 4 is a fuel injection control routine also executed by the electronic control circuit. 5, FIG. 5 is a flowchart of a TAU calculation process which is one step of the fuel injection control routine, FIG. 6 is a flowchart of an RSTEP calculation routine also executed by the electronic control circuit, and FIG. 7 is a command opening TSTEP. FIG. 8 is a timing chart showing the operation of the embodiment. M1 internal combustion engine, M2 operating state detecting means M3 fuel injection means M4 exhaust system M5 intake system M6 exhaust recirculation path M7 control valve M8 exhaust recirculation Means M9 ... Instructed opening output means M10 ... Deceleration state determination means M11 ... Actual opening detection means M12 ... Difference determination means M13 ... Fuel injection stop means 2 ... Internal combustion engine 4 ... Intake pipe 16 ... ... intake pressure sensor, 18 ... exhaust pipe 24 ... EGR device, 26 ... exhaust gas recirculation path 28 ... EGR valve, 38 ... rotational speed sensor 46 ... electronic control circuit, 48 ... fuel injection valve

Continued on the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical display F02M 25/07 550 F02M 25/07 550R

Claims (1)

(57) [Claims] An operating state detecting means for detecting an operating state of an internal combustion engine including a load, receiving a detection result of the operating state detecting means, and injecting a fuel amount corresponding to a load of the internal combustion engine to the internal combustion engine. A fuel injection means, and a control valve disposed in an exhaust recirculation path connecting an exhaust system and an intake system of the internal combustion engine, and controlling an opening degree of the control valve according to a control signal from the outside to control exhaust gas. An exhaust gas recirculation unit that recirculates a part of the exhaust gas to the intake system; and a detection result of the operating state detection unit. A fuel injection control device for an internal combustion engine with an EGR device, comprising: an instruction opening output means for outputting to the means; and determining whether or not the internal combustion engine is in a deceleration state based on a detection result of the operating state detection means. Deceleration state determination means; An actual opening detection means for detecting an actual opening of the control valve of the air recirculation means; and an instruction opening output by the instruction opening output means from the actual opening detected by the actual opening detection means. Difference determination means for determining whether the difference obtained by subtracting the degree is equal to or greater than a predetermined value, and the deceleration state determination means determines that the vehicle is in a deceleration state,
An internal combustion engine with an EGR device, further comprising: fuel injection stop means for stopping the fuel injection supply in the fuel injection means when the difference determination means determines that the difference is equal to or greater than a predetermined value. Engine fuel injection control device.